Book/Report

FZJ-2019-03660

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png In-situ-Messung langlebiger Spurengase in der untersten Stratosphäre: Entwicklung und Anwendung einer flugzeuggestützten gaschromatographischen Nachweismethode

Bujok, O. (Corresponding author)FZJ*

1998
Forschungszentrum Jülich, Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/22446

Report No.: Juel-3517

Abstract: In the framework of this thesis, an airborne gas chromatograph for the in-situ measurement of long-lived tracers has been developed. The $\underline{G}$as c$\underline{H}$romatograph for the $\underline{O}$bservation of $\underline{S}$tratospheric $\underline{T}$racers (GHOST) simultaneously measures either N$_{2}$O and CF$_{2}$CI$_{2}$ (CFC-12) or CFC-12 and CFCl$_{3}$ (CFC-11) with a time resolution of 2 min for both modes, a 1$\sigma$-precision of better than 0.7 %, and an accuracy of better than 1.7 %. Detection limits are sufficiently low to allow precise measurements of these species up to altitudes of at least 22 km. In the frame of the STREAM III ($\underline{S}$tratosphere $\underline{TR}$oposphere $\underline{E}$xperiment by $\underline{A}$irborne $\underline{M}$easurement) measurement campaigns in May 1996 and March 1997, GHOST was operated onboard a Cessna Citation II, flying at altitudes up to 13 km. During these campaigns, the up to now largest data set of CFC measurements in the lowermost stratosphere at northeren mid and high latitudes was obtained. Together with additional tracer measurements during STREAM III these data were analyzed with regard to thie following subjects: On the basis of the complete data set, $\textbf{the atmospheric residence time of N$_{2}$O}$ was determined relative to the atmospheric residence time of CFC-11. With respect to an atmospheric CFC-11 residence time of 50 ± 5 years, a value of 101 ± 11 years is calculated for N$_{2}$O. $\textbf{The transport of tropospheric air masses into the lowermost stratosphere at mid latitudes}$ was investigated considering CFC-12/H$_{2}$O-correlations. The data obtained in 1996 at mid latitudes indicate that tropospheric air masses from the extratropics are transported into the lowermost stratosphere on isentropic surfaces up to 350 K in the vicinity of the polar front. This transport leads to the formation of an exchange layer directly above the tropopause. The thickness of this layer is substancially enhanced in the vicinity of the polar front. A detailed case study has been carried out using $\textbf{the reverse-domain-filling (RDF) method for the interpretation of high resolution tracer measurements in the tropopause region}$. During a measurement flight in the vicinity of the polar front, the tracer measurements with GHOST demonstrate that the aircraft crossed a mesoscale, vertically coherent filament of tropospherically influenced air within the lowermost stratosphere several times. For this filament, the analyzed potential vorticity (pv) along the flight track does not show the expected corresponding negative pv anomaly, whereas the pv reconstructed with RDF (rpv) shows such a feature that corresponds to the tracer measurements not only regarding its positioning but also regarding its amplitude. It is furthermore shown that the trajectory length chosen within the RDF method is a key parameter for the degree of correspondence between rpv and the tracer measurements. For the considered case, the trajectory length assumes an optimum value of approximately 2 days.

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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